Screen printing machine comprising endless templates



1960 R. KRAFf 2,947,246

SCREEN PRINT ING MACHINE COMPRISING ENDLESS TEMPLATES Filed Sept. 29,1958 2 Sheets-Sheet 1 IN VENTGQ RUPERT K RAFT a) War,

AT 7' DIP/VH5 Filed Sept. 29, 1958 Aug. 2, 1960 R. KRAFT 2,947,246

' SCREEN PRINTING MACHINE COMPRISING ENDLESS TEMPLATES 2 Sheets-Sheet 2IN vs/vroz RUPRT KRAFT B) 50 5min y vdmin ATTORNEYS like is added tothe'template varnish.

SCREEN PRINTING MACHINE COMPRISING ENDLESS TEMPLATES Rupert Kraft, 4 Dr.Premstrasse, Kufstein, Austria F iled Sept. 29, 1958, S61. Ni]; 763,857Claims priority, application Austria Oct. 1, 1957 11 Claims. (Cl.101-122 In screen printing machines comprising endless templates,dificulties were previously involved inthe storage of the template beltsbecause the material which remains on the inside of the templates behindthe doctor means, namely, ink, binder or other material, such as kaolinfor paper treatment of etching agents for textiles was forced by theguide rollers through the template to the outside thereof and gave anundefined, smeared appearance to the outline of the patterns. This isdiagrammatically shown by way of example in Fig. 1. The material to beprinted is pasted on a blanket and printed by means of a template movedaround three rollers arranged in a triangle. The ink or binder or othermaterial is applied from the inside and scraped by means of a doctor. Asis apparent from the drawing, ink remains nevertheless on the inside ofthe template. This ink accumulates near the right-hand tension roller toform a wedge, which is then: forced through the template to the outsidethereof. Similar wedges form at the two other tension rollers so thatthe endless template comprises on the outside ink or binder forcedthrough the template and the patterns are not reproduced with thedesired definition on the material to be printed.

This known screen printing machine has the additional disadvantage ofrequiring a device which ensures synchronism between the blanket withthe material pasted thereon and the endless template. Inrnulti-coloredprinting using several template belts, therefore, it isextremelydifiicult to provide registry of the patterns produced by thesever al templates -Besides, it is not very simple to exchange templatesbecause the tension rollers lie on the inside thereof. It is diifcult tobring the endless template belt into contact with the blanket and thematerial pasted thereon because the tension roller shown on the right inthe drawing squeezes the scraped patterns whereas the tension rollershown on the left in the drawing transmits the ink etc. urged to theoutside of the belt in an undesirable manner unto the material. I

It is an object of the invention to eliminate these disadvantages of theknown screen printing machine. With this object in mindit is proposed touse templates of material which is responsive to magnetic forces and toprovide externally disposed magnetic (permanentmagnetic orelectromagnetic) rollers for guiding the tern plates and a magnetic(permanent-magnetic or electromagnetic) faceplate as a blanket printingtable. Thus all disadvantages of the internal tension rollers areeliminated. A suitable material for the templates is steel or iron wiremesh having a corrosion resisting surface, or even one of the usualmaterials if iron powder or the Fabrics for printing templates whichconsist partly or entirely of metal wire have already been proposed butonly for improved wear, not in combination with permanent-magnetic orelectromagnetic rollers and/or faceplates.

' Patented Aug. 2., 1960 Illustrative embodiments of screen printingmachines constructed according to the invention are shown in thedrawings in diagrammatical side elevation.

Fig. 2 is a machine for two-color printing,

Fig. 3 is a machine for three-color printing, with arcuately arrangedrollers-just as that of Fig. 2.

Fig. 4 shows a machine having only one roller.

Fig. 5 shows the machine comprising three rollers arranged in atriangle.

Fig. 6 shows "a machine for three-color printing having a verticalarrangement of the faceplate tables, and

Fig. 7 shows a machine for two-color printing having printing tables'ina circular arrangement.

Fig. 8 is a circuit diagram showing the means for controlling themagnetic condition of the printing table and guide rollers. In allfigures, like parts bear like reference numerals.

The embodiment according to Fig. 2 comprises an electromagneticfaceplate table 1, over which the material 4 pasted onto the blanket 3is moved. Above the faceplate table an arcuate series of rollers 5 ismounted on an appropriate frame, which are also magnetizable byelectromagnets, not shown. Each roller'5 is connected by an endlessdrive chain to the adjacentroller. One of the rollers 5, e.g., themiddle one, carries a handwheel 6 for adjusting the template in themanner to be described hereinafter. The roller frame 7 can be later allydisplaced by anadditional handwheel 8'.

As has been mentioned hereinbefore the endless template 9 is responsiveto magnetic forces and when the electromagnet is energized the templateis forced against the arcuately arranged rollers 5 and the faceplatetable 1. Thus, the template is caused to assume approximately theconfiguration shown in Fig.- 2. The ink, the binder 10 or othersubstance are again applied in the usual manner to the inside of thetemplate. 11 is a suitable doctor of any desired type.

- To adjust the template in the longitudinal direction the printingtable 1 is only slightly energized whereas the rollers 5 are fullyenergized. The handwheel 6 can now be turned to displace the templatesin the longitudinal direction into registry with the patterns of thepreceding or succeeding template belts. By means of the handwheel 8 theframe for the templates can be later: ally displaced when the printingtable l is onlyv slightly energized. Thus the template can be given thecorrect lateral adjustment. Then, the printing table 1 is fullyenergized and the material is caused to run through the machine. Thetemplate is strongly forced against the printing table 1 by theelectromagnetic forces acting through theblanket 3 and the goods 4 andfollows without slip the movements of the driven blanket 3 and thematerial 4 pasted thereon, whereby it slides over the printing table andis colored with the ink.10 etc. applied to the inside. Because thetemplate is guided only on the outside, the above-mentioned soiling oftheoutside of the template by ink etc. forced through the template is nolonger possible.

Another advantage of the construction according to the invention residesin that the templates can easily be replaced because no machine part isarranged inside the template with the exception of the doctor means.

Fig. 3 shows the construction of a machine for threecolor printing. Eachof the three inking devices comprises a stationary doctor consisting ofa doctor roller 12 'and a magnetic beam 13. The endless blanket 3 runsaround the two blanket rollers 14, one of which .is continuously drivenwhereas the other one serves for pulled against the faceplate 1 andupwardly through the roller to assume the triangular configuration shownin the drawing.

The embodiment shown in Fig. 5 differs from that of Fig.v 4 only in thattwo additional rollers 5 are arranged on the two lower corners of thetriangle formed by the template. v

Fig. 6 shows a three/color printing machine which differs from that ofFig. 3 only in that the'faceplate tables 1 are vertical so that thethree inking devices are arranged one below the other. Hence, thematerial is printed in a vertical condition. A drier 15 is associatedwith the opposite run.

Fig. 7 shows a machine for two-color printing, in which the printingtables 1 consisting of segments of a. circle are arranged within ahollow cylinder 16 which consists of nonmagnetic material of low wallthickness and is freely rotatably driven.

Fig. 8 shows a circuit diagram of means for independently controllingthe magnetic condition of the printing table 1 and of the rollers 5,only one of which is shown, respectively.

A direct current source 21, e.g., the output of a rectifier (not shown)has two parallel circuits connected thereto. The first of these circuitscomprises in series a switch 22', a resistor 23 which can be shunted bya switch 24, and a magnet coil 25 associated with the face plate 1. Thesecond circuit includes, again in series, a switch 26, a resistor 27which can be shunted by a switch 28, and a magnetcoil 29 associated withthe roller 5. The full energization applied to the coils 25 and 29 whenthe switches 22, 24, 26 and 28 are closed can be selectively reduced byopening the switch 24 and/ or 28. It is understood that the switches 22,24, 26, 28 can be combined in a single cam-controlled switch which willautomatically perform the desired switching operations in apredetermined cycle, as will be understood by a man skilled in the art.

Various modifications are possible within the scope of the invention.For instance, the electromagnets could be replaced by permanent magnetswhich can be disengaged. Instead of the fiat printing table, a rollcould be used around which the material and the template are moved.

What is claimed is:

'1. A screen printing machine which comprises a magnetizable printingtable, at least one endless template of material responsive to magneticforces, magnetic rollers engaging the outside of said template forguiding said template past said table adjacent thereto to cause it to beattracted by magnetic forces produced by said table, and means formoving material to be printed between said template and said printingtable to cause said template to be moved in the same direction and atthe same speed as said material. I

2. A screen printing machine as set forth in claim 1, in which saidprinting table comprises permanent-magnetic means for producing saidmagnetic forces.

3. A screen printing machine as set forth in claim 1, in which saidprinting table comprises electromagnetic means for producing saidmagnetic forces.

4. A screen printing machine as set forth in claim 1, in which saidmagnetic rollers comprise permanentmagnetic means.

5. A screen printing machine as set forth in claim 1, in which saidmagnetic rollers comprise electromagnetic means.

6. A screen printing machine as set forth in claim 1, in which at leastone of said magnetic rollers is spaced from said printing table.

7. A screen printing means as set forth in claim 1, in which saidprinting table and said rollers comprise electromagnetic means, andwhich comprises means for energizing said electromagnetic means andcontrol means for independently varying the energization of saidelectromagnetic means of said printing table and rollers, respectively.

8. A screen printing machine as set forth in claim 1, which comprisesmeans arranged to couple said rollers for rotation.

9. A screen printing machine as set forth in claim 1, in which saidmeans for moving said material comprise a blanket, which is at leastpartly vertically disposed.

10. A screen printing machine as set forth in claim 1, which saidmagnetic table comprises arcuate segments of a circle, there being ahollow cylinder consisting of nonmagnetic material having a thin wallsurrounding said table and being freely rotatably driven by said movingmeans.

.11. A screen printing machine as set forth in claim 1, which comprisesmeans for independently modifying the magnetic condition of saidprinting table and rollers, respectively.

References Cited in the file of this patent UNITED STATES PATENTS

